Glow plug for internal combustion engines



y 3, 1934- H. A. DORNER 1,957,762

GLOW PLUG FOR INTERNAL COMBUSTION ENGINES Filed Sept. 16. 1929 5 as f a F I Jmmfloc HERMHNN LH. 1703mm.

Patented May 8 1934 GLOW PLUG FOR INTERNALCOMBUSTION ENGINES Hermann I. A. Dorner, Hanover, Germany, as-

signor, by mesne assignments, to Packard Motor Car Company, Detroit, Mich a corporation of Michigan Application September 16, 1929, Serial No. 392,808

12 Claims.

This invention relates to internal combustion engines and more particularly to devices, known as glow plugs, for assisting the combustion of fuel charges in Diesel type engines.

Glow plugs usually include a body which is screwedinto the cylinder wall, an electrode and a projecting coiled resistance wiresecured at one end to the electrodeand at the other end to the body. The resistance wire is arranged in the engine cylinder to permit atomized fuel to be sprayed thereagainst, and therefore the heat in the cylinder is centralized in a zone surrounding the Wire. The heat developed in the Diesel type engine is suificient to cause the resistance wire to glow even when it is not connected to the source of electrical energy, and the explosive shocks and consequent vibration cause the incandescent resistance wire to break after very short usage at its points of connection with the electrode and the glow plug body.

It is an object of my invention to increase the life of glow plugs employed with Diesel type engines.

Another object of my invention is to provide a glow plug for internal combustion engines in which the resistance wire is formed and attached to the electrode and the body in a manner such that bending moments at the points of its con nection are reduced to a minimum.

Another object of my invention is to increase the life of glow plugs by forming the resistance wire with enlarged ends so that the portions adjacent the attachment to the electrode and the body will withstand vibration.

These and other objects of the invention will.

appear from the following description taken in connection with the drawing which forms a part of this specification, and in which:

Fig. 1 is a side elevation of a glow plug incorporating my invention,

Fig. 2 is a medial sectional view of the same,

Fig. 3 is a side elevation of the resistance wire prior to winding.

Referring now to the drawing by characters of reference, 10 represents a core which will be termed the electrode. A terminal member 11 surrounds one end of the electrode, and a flange 12 is provided on the electrode to prevent endwise displacement of the terminal. The electrode is provided with an enlarged end 13 which forms a shoulder 14, and an insulating collar 15 surrounds the electrode intermediate the terminal 11 and the shoulder 14. Insulating means 16, composed of a plurality of mica discs, surrounds the end of the collar adjacent the shoulder 14 while a plurality of mica discs 17 are arranged axially around the collar 15 adjacent the terin the body. A copper gasket 22 is arranged at the tapered joint between the nut and body. The body 18 is provided with external threads at one end so that it can be screwed into an aperture in the cylinder of an internal combustion engine,

while the other end 21 is provided with flattened surfaces for the reception of a wrench.

The electrode extends substantially through the body 18 and such body is hollow so that the electrode therein will be spaced from thev interior walls thereof, such space being provided to permit the circulation around the enlarged end of the electrode which tends to reduce the temperature thereof when the engine is in operation.

My invention consists of associating a resistance wire with the structure above described, so that the life of the glow plug is materially in creased. In accomplishing this result, I propose to form the ends of the resistance wire 23 of a larger diameter than the central or heating portion. The end 24 of the wire is shown substantially twice as large in diameter as the central portion of the wire, while the end 25 is about one half again the diameter of the central portion of the wire. The larger endof the wire extends into an axial recess 26 in the end of the electrode section 13 and is secured therein in a suitable manner, such as by welding. The other end 25 of the wire extends into a recess 27 formed in the end of the body, and is secured therein in a suitable manner, such as by welding.

The end portions of the wire are cylindrical where they enter and are connected to their supports and from those points the wire tapers gradually to the heating portion of the wire. The end 24 of the resistance wire extends axially of the electrode and projects in this relation the full length of the wire structure beyond the end of the body 18, and is then coiled in a direction toward the end of the body and around the axially extending portion forming substantially a circular coil 28.

It will be seen that the enlarged ends extend beyond the ends of the body and the electrode, and that the tapered portion of the end 24 extends substantially to the point where the coil is started and that the tapered portion of the 2 c end extends into the base convolution oLthe coil. This construction increases the lite oi the glow plug because the thickness oi the wire at the points oi its connection provide strength which will withstand severe vibration for a long period of engine operation. Furthermore, the enlarged ends of the wire provide for a gradual lowering of the temperature in a direction toward the electrode and the body so that heat will not be concentrated to the highest degree at the I points of connection between the resistance wire andtheelectrodeandthebody,sothattheresultant temperature condition will materially increase the liie oi the wire. 1

It may be desirable to connect both ends of the resistance wire to electrodes, and in such event the wire ends are formed and attached in the same manner as the end or the wire connected to the electrode as described heretofore.

Although the invention has been described in connection with a specific embodiment, the principles involved are susceptible of numerous other applications, which will readily occur to persons skilled in the art. The invention is therefore to be limited only as indicated by the scope of the appended claims.

What I claim is:

i, A glow plug for internal combustion engines comprising a bodyfan electrode insulated from and carried by the body, and a one piece bare resistance' wire coiled exteriorly oi the body, said wire having enlarged ends secured directly one to the electrode and the other to the body.

. 2. A glow plug for internal combustion engines comprising a body, an electrode insulated irom and carried by the body, and a bare resistance wire coiled exteriorly oi the body, said wire having one end enlarged integrally and secured to the electrode and the other end secured to the body. 3. A glow plug for internal combustion engines comprising a body, an electrode insulated from and carried by the body, and a bare resistance wire coiled exteriorly oi the body, one end of the wire being secured to the electrode and the other end being enlarged integrally and secured to the body.

4. A glow plug for internal combustion engines comprising a body, an electrode insulated from and carriedby the body, andabareresistance wire having integral enlarged ends secured one to the electrode and one tothe body, the central portion of said wire being of uniform diameter and formed in a coil. 5. A glow plug ior internal combustion engines 5 comprising a body, an electrode insulated from and carried by the body, and a bare resistance wire having integral enlarged ends of difi'erent diameter, the end or larger diameter being sc cured to'the electrode and the other end being secured to the body. 4

8. A glow plug for internal combustion engines comprising a body and an insulated electrode, and a bare resistance wire having a coiled heating portion and integral enlarged ends secured to the body and electrode respectively, the enlargement of one of the ends extending to a point beyond the first bend in the wire.

7. A glow plug for internal combustion engines comprising a body and an insulated electrode, and a bare resistance wire having a coiled heating portion and integral enlarged ends secured to the body and electrode respectively, the wire tapering from the maximum enlargement of one 0! its ends to a point beyond the first turn in the wire.

8. A glow plug for internal combustion engines comprising a body and an insulated electrode, and a bare resistance wire connected by its ends to the body and electrode respectively, the heating portion oi said wire being smaller in diameter than the integral end portions and the wire tapering from its end connections to the heating portion.

9. A glow plug for internal combustion engines comprising a body and an insulated electrode, and a bare resistance wire connected by its ends to the body and electrode respectively, the heating portion oi said wire being coiled and being smaller 'in diameter than the integral end portions and the wire tapering irom at least one oi its ehd connections to a point beyond the first bend in the wire.

10. A glow plug for internal combustion engines comprising a body and an insulated electrode, and l a bare resistance wire connected by its ends to 1 0 the body and electrode respectively, said resistance wire being integrally enlarged at the point where it is connected to the electrode.

11. A glow plug for internal combustion engines comprising a body, an electrode insulated 5 irom and carried by the body, and a one-piece bare resistance wire secured at its ends to the body and electrode respectively, the middle portion of the wire being uniform in diameter and smaller than the end portions, and the wire having taper- 1 ing portions intermediate the end portions and the middle portion.

12. A glow plug for internal combustion engines comprising a body, a central insulated elecv trode, and a one-piece bare resistance wire directly connected by its ends to said body and said electrode respectively, said wire extending axially outward from said electrode and then bent to form a coil about the outwardly extending part, said wire tapering from a relatively large diameter where connected to the electrode to a mini- ,mum diameter at the coil part.-

nmusrm I. A. DORNER. 

